Fuel tank of thermoplastic material with functional installation fitments for air intake and venting, for fuel take-off and the like

ABSTRACT

The invention concerns a fuel tank of thermoplastic material, comprising functional installation fitments for air intake and venting, for fuel take-off or the like, which is distinguished in that at least one functional installation fitment is connected to the inside wall of the container in material-bonded relationship in such a way that the functional installation fitment defines with the container wall a volume separated from the filling volume of the container in such a way that the inside wall of the container serves directly as a boundary wall of said volume.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/957,792, filed Dec. 17, 2007 which claims the benefit of U.S.Provisional Application 60/870,231 filed Dec. 15, 2006.

FIELD

The invention concerns a fuel tank of thermoplastic material withfunctional installation fitments for air intake and venting, for fueltake-off or the like.

BACKGROUND

The invention concerns in particular an extrusion blow molded fuel tankof thermoplastic material. Such tanks are usually produced in one piecefrom one or more tubular preforms which are applied against the wall ofa multi-part molding tool by means of gas pressure or are expanded inthe tool. Depending on how the operation of shaping the tank in the toolis effected, installation fitments are introduced into the tank eitherafter it is finished through one or more mounting openings and fixedtherein or the functional components are already introduced into thetank during the operation of shaping it. If the tank is blow molded froma tubular preform, the diameter of the preform is generally such that itcan be extruded over an installation fitment holder with installationfitments carried thereon.

Welding installation fitments to the inside wall of the tank in thefirst heat when shaping the tank has proven to be disadvantageous inparticular when dealing with relatively large installation fitments suchas surge containers or the like as cooling of the container wall afterthe article is finished is impeded in the regions in which weld surfacesare provided on the inside wall of the container. If for example in thefuel tank a surge container is welded with its bottom support surfaceover a large area to the inside wall of the fuel tank, cooling of thetank wall when cooling down the article is hindered over a large area.In particular internal cooling of the finished article by gas/airflushing is adversely effected. The accumulation of material at theinside wall of the container, being greater in region-wise manner,possibly causes shrinkage distortion of the material which is visibleexternally on the tank.

In principle however, for reasons of production engineeringsimplification, it would be desirable to provide one-piece tanks madefrom thermoplastic material, which are equipped with installationfitments or installation components which are joined to the tank wall inmanufacture in the first heat.

Therefore the object of the invention is to provide a fuel tank ofthermoplastic material having functional installation fitments for airintake and venting, for fuel take-off or the like, in which thefunctional components are connected to the container wall and in whichthe functional components were connected to the tank during shapingthereof in the first heat, the aim being that the tank should notinvolve the above-mentioned disadvantages.

That object is attained by a fuel tank of thermoplastic material of thekind set forth in the opening part of this specification, which isdistinguished in that at least one functional installation fitment isconnected to the inside wall of the container in material-bondedrelationship in such a way that the functional component defines withthe container wall a volume separated from the filling volume of thecontainer in such a way that the inside wall of the container servesdirectly as a boundary wall of said volume.

SUMMARY

The invention can be summarised to the effect that there are introducedinto the fuel tank those functional components which acquire fullfunctionality only in a condition of co-operation with the inside wallof the container, so that the inside wall of the container takes over apart of the functionality of the component in question and also acts asa boundary wall of the functional component. As functional installationfitments, it is possible to provide for example profile portions whichare welded to the inside wall of the container in such a way that, withthe inside wall of the container, they form volumes or passages whichare closed at least in portion-wise manner.

By way of example the profile portions can be of semicircular, U-shapedor V-shaped configuration in cross-section.

In a particularly preferred variant of the invention there is providedat least one surge container for a fuel pump, which surge container isopen on its side towards the inside wall of the tank in the installationposition and the boundary wall thereof being connected therearound tothe inside wall of the tank in material-bonded relationship. Thateliminates an accumulation of material at the inside wall of the tank,which occurs by virtue of the bottom of the surge container bearing overits full surface area against the inside wall of the fuel tank. In thevariant according to the invention the fuel tank itself forms the bottomof the surge container. In that way, it is advantageously possible touse a surge container which is at least partially closed on it's sideremote from the inside wall of the tank. Such a surge container can befor example in the form of a plastic component produced in one piece byinjection molding. The possibility of being able to produce the surgecontainer as an integral component or in one piece is afforded inparticular by virtue of the fact that the surge container is closed bythe wall of the fuel tank upon being mounted or connected to the insidewall of the fuel tank.

It will be appreciated that the fact that the side of the surgecontainer that is remote from the inside wall of the tank is to be of aclosed configuration is to be interpreted as meaning that the surgecontainer can have connections, nipples or apertures for lines which areto pass into or out of the surge container.

Desirably the boundary wall of the surge container is provided with aperipherally extending fixing flange at the side that is towards theinside wall of the tank in the installation position.

In order to achieve a peripherally extending connection which is as goodas possible, involving a material-bonded relationship, between thefixing flange on the one hand and the inside wall of the tank on theother hand, the joining surface of the fixing flange can be of aprofiled configuration. Alternatively the joining surface of the fixingflange can be provided with melting projections and/or melting extensionportions. That is used to denote thin material projections or materialextension portions, ribs or limbs which have a comparatively slightthermal capacity and which, when the parts in question of the joiningsurface come into contact with the inside wall of the tank which isstill hot, melt because of their slight thermal capacity and thuscontribute to forming a reliable welded connection.

The boundary wall of the surge container can be of a flexible nature atleast in region-wise manner and at least portion-wise in relation to theperiphery of the surge container. By way of example the boundary wall ofthe surge container may have a peripherally extending film hinge or thelike so that the angle between the fixing flange and the container wallis variable. It is thus possible advantageously to compensate forunevenness and irregularities in the inside wall of the tank. As isknown, components which are just extrusion blow molded involve slighttolerances in respect of wall thickness, which are to be taken intoconsideration when designing installation fitments to be welded to thetank wall, at least in relation to those installation fitments whichmust be welded peripherally in sealing relationship with the inside wallof the tank, as must be the case for example with a surge container.

If profile portions for forming passages or receiving means for linesare to be provided as the installation fitment, it is possible for thoseinstallation fitments to be so designed overall in terms of their wallthickness that tolerances in wall thickness of the inside wall of thetank can be compensated for, when joining the installation fitments.

DESCRIPTION OF THE DRAWINGS

The invention is described hereinafter by means of an embodiment by wayof example which is illustrated in the drawing in which:

FIG. 1 shows a view in section through a fuel tank according to theinvention,

FIG. 2 shows an enlarged sectional view of the detail II in FIG. 1,

FIG. 3 shows an alternative configuration of the fixing flange shown inFIG. 2 of the surge container fixed in the fuel tank,

FIG. 4 shows a further configuration of the surge container in theregion of its fixing to the inside wall of the tank,

FIG. 5 shows a fourth variant of the surge container in the region ofits fixing to the inside wall of the fuel tank,

FIG. 6 shows a fifth embodiment according to the invention,

FIG. 7 shows a sixth embodiment according to the invention,

FIG. 8 shows a partial section through the surge container of the fueltank according to the invention, in which a non-flat support and fixingsurface on the inside wall of the container is shown on an exaggeratedscale,

FIGS. 9 and 10 show a seventh embodiment according to the invention, and

FIGS. 11 and 12 show an eighth embodiment according to the invention.

DETAILED DESCRIPTION

FIG. 1 shows a simplified sectional view of a fuel tank 1 according tothe invention. The fuel tank 1 is in the form of an extrusion blowmolded plastic hollow body. It was produced by extrusion blowing of anoverall six-layer co-extrudate of thermoplastic material with at leastone barrier layer for hydrocarbons. In that case, two preforms in webform of thermoplastic material were extruded between the opened parts ofa blow molding tool having a total of three parts. The blow molding toolfor the production of such a fuel tank 1 includes at least two outermolds and a central mold, wherein each of the outer molds forms a cavityportion which defines a respective half of the hollow body to beproduced. In a first step in the method the respective preforms in webform are extruded or arranged between an outer mold and the central moldrespectively. In that position the outer molds are closed against thecentral mold. That results in the formation of a closed mold cavity,wherein the preforms are each drawn into the respective cavity portionat the respective outer mold by means of gas pressurisation of thecentral mold and/or evacuation of the outer molds. Component carrierswith components disposed thereon are preferably provided in the centralmold on a displaceable frame. The component carriers are arrangeddisplaceably in the central mold by way of for example hydraulically orpneumatically actuable cylinders. By means of the component carriersfunctional components are placed within the tank in such a way that theyare fitted for example into suitable receiving means at the inside wallof the tank.

Alternatively it is possible in that way for functional components ofplastic material to be welded to the inside wall of the tank, while thatwall is still plastic, during the operation of shaping the tank.

It will be appreciated that a fuel tank as is described in detailhereinafter can also be obtained by deep drawing or thermoforming, inwhich respect also functional components can be welded to the insidewall of the tank in such a process.

The container shown in FIG. 1 is in the form of a fuel tank 1. Theprinciple described herein can however be readily applied to otherclosed containers of plastic material with functional components to beprovided therein.

The fuel tank 1 is shown in greatly simplified form. It may include theusual air intake and venting lines as well as at least one fillingconnection and lines for fuel take-off to an internal combustion engineof a motor vehicle (not shown). Usually the fuel is conveyed by way of aplurality of suction jet pumps from various sub-volumes of the fuel tank1 which is shown here for reasons of simplification only with one singlevolume into a surge container 2 which is arranged in the fuel tank 1.Arranged in known manner within the surge container 2 which is alsoreferred to as a roll pot is at least one electric fuel delivery pumpwhich conveys fuel from the volume of the surge container to the engineof the internal combustion machine. The fuel pump is also not shown herefor reasons of simplification. The surge container 2 serves to ensurethat the fuel pump is supplied with fuel during all travel conditions ofthe vehicle, that is to say in acceleration, deceleration and whennegotiating bends.

In accordance with the invention it is provided that for example thesurge container 2 is connected to the inside wall 3 of the fuel tank 1in such a way that it defines a volume which is separate from thefilling volume of the fuel tank 1, wherein the inside wall 3 of thecontainer serves directly as the boundary wall of the volume. In otherwords, the surge container 2 in the embodiment described here does nothave a bottom. The bottom is formed by the inside wall 3 of the fueltank 1, wherein the surge container 2 is provided on its side towardsthe inside wall 3 with a fixing flange 4 which is peripherally welded insealing relationship to the inside wall 3 of the fuel tank 1. That makesit possible for the surge container 2 to be in the form of a one-pieceinjection-molded component on which all essential elements are molded.In the case of a conventionally designed surge container 2 with abottom, it is necessary for it possibly to be provided with a coverfastener which is then latched to the surge container 2. That isnecessary in order to pre-assemble the fuel pump and possibly a fuellevel sender or the like in the surge container 2 before it isintroduced into the fuel tank 1.

According to the invention it is provided that the surge container 2 maybe connected to the inside wall 3 in material-bonded relationshiptherewith during the procedure for shaping the fuel tank 1. Morespecifically, as already mentioned in the opening part of thisspecification, this may be done in such a way that the inside wall 3forms a boundary wall of the surge container 2.

As can be seen from FIGS. 2 through 7, the boundary wall 5 of the surgecontainer 2 in the region of the fixing flange 4 can be of an L- orT-shaped profile with a joining surface 6 which faces towards the insidewall 3. In the case of the surge container 2 which is desirably of around configuration in cross-section, the joining surface 6 of thefixing flange 4 is of a fully peripherally extending configuration sothat it can be welded at the edge side in sealing relationship to theinside wall 3 of the fuel tank 1.

For that purpose the joining surface 6 is provided with welding ribs orwelding protrusions 7 (See FIGS. 3-6) whose thermal capacity is suchthat, upon coming into contact with the wall 3 of the fuel tank 1 whenit is still hot and plastic during the procedure for shaping the fueltank, the ribs or protrusions 7 melt and thus form an intimatematerial-bonded connection between the inside wall 3 on the one hand andthe joining surface 6 on the other hand.

In order to be able to compensate for wall thickness tolerances in thecontainer wall or indeed unevenness and irregularities of the insidewall, the boundary wall 5 may be of a flexible configuration, as shownin FIGS. 4 through 8, in such a way that the fixing flange 4 may beflexible or movable within certain limits and can assume for example theangled (not right-angled) position with respect to the boundary wall 5of the surge container 2, which is shown in FIG. 8 on the right-handside. The flexibility of the fixing flange 4 in relation to the boundarywall 5 can be achieved in various ways, for example by the provision ofa peripherally extending film hinge having a curved (FIG. 5) or thinned(FIGS. 4, 6 and 8-12) cross-section. Alternatively, the surge containercan have been produced from various plastic materials, in which case forexample plastic materials of varying hardness can be provided over theheight of the boundary wall 5 (hard-soft-hard for example). That maypermit height compensation in respect of any projections in the insidewall 3 of the fuel tank 1. Depending on the respective width andconfiguration of the fixing flange 4 load relief slots can be providedtherein to avoid unacceptable stresses, caused by the circular ringshape of the joining surface 6.

The invention has been described hereinbefore with reference to a surgecontainer 2.

As is also shown in FIG. 1, it is also possible to provide profileportions 9 as installation fitments in accordance with the invention.The profile portions 9 were welded to the inside wall 3 of the fuel tank1 during the shaping thereof, in such a way that they form either closedpassages for air and/or fuel or for receiving lines which are of roundcross-section. In the latter case the profile portions 9 a, b embraceand hold lines accommodated therein, only in region-wise manner.

The profile portion 9 a shown in FIG. 1 is of a V-shaped cross-sectionwhile the profile portion identified at 9 b in FIG. 1 is in the form ofa U-shaped cross-section. Other geometries are readily conceivablewithin the scope of the invention. The profile portions 9 a, b make useof the underlying idea of the invention, of using the inside wall 3 ofthe container as a boundary wall of a volume to be separated from thecontainer. That saves on clamping or latching retaining fixings forlines.

As shown in FIGS. 9 and 10, the inside wall 3 of the fuel tank can beprovided with inwardly projecting ribs 10 or the like, which co-operatewith corresponding grooves 10 a of the surge container 2 and whichfacilitate immovable fixing thereof on the inside wall 3 of the fueltank 1.

It will be appreciated that, instead of the ribs 10 on the inside wall 3of the fuel tank 1, it is also possible to provide there grooves whichco-operate with corresponding ribs on the surge container 2.

FIGS. 11 and 12 show a variant of the surge container which comprises aplastic material which is not compatible with the inside wall 3 of thefuel tank 1, in the sense of being weldable thereto. In that case,provided between the joining surface 6 of the boundary wall 5 and theinside wall 3 of the fuel tank 1 is a hot melt adhesive 11 or anothersuitable bonding agent which in contact with the hot inside wall 3 ofthe fuel tank 1 produces a connection involving a material-bondedrelationship.

LIST OF REFERENCES

-   1 fuel tank-   2 surge container-   3 inside wall-   4 fixing flange-   5 boundary wall-   6 joining surface-   7 welding protrusions-   8 relief slots-   9 a, b profile portions-   10 ribs-   10 a grooves-   11 hot melt adhesive

1. A method for forming a container of thermoplastic material, having aninside wall and a filling volume, and including functional installationfitments, comprising: connecting one functional installation fitment tosaid inside wall of the container by melt-bonding in such a way that thefunctional installation fitment defines with the container wall a secondvolume separated from the filling volume of the container in such a waythat the inside wall of the container serves directly as a boundary wallof said second volume, wherein said melt-bonding of said at least oneinstallation fitment to said inside wall of said container occurs whilesaid container wall is still plastic and during the operation of shapingthe tank.
 2. The method as set forth in claim 1 wherein profile portionsare provided as functional installation fitments, being melt-bonded tothe inside wall of the container in such a way that they form volumes orpassages which are closed at least in portion-wise manner therewith,wherein said melt-bonding of said profile portions to said inside wallof said container occurs while said container wall is still plastic andduring the operation of shaping the tank.
 3. The method as set forth inclaim 2 wherein said profile portions are of semicircular, U-shaped orV-shaped cross-section.
 4. The method as set forth in claim 1 whereinsaid at least one functional installation fitment comprises a surgecontainer for a fuel pump, said surge container including a boundarywall and at least one side and is open on the side that in theinstallation position faces towards the inside wall of the container andsaid boundary wall is peripherally connected in melt-bonded relationshipto the inside wall of the container during the shaping of the tank. 5.The method as set forth in claim 4 wherein the surge container is atleast partially closed on the side remote from the inside wall of thecontainer.
 6. The method as set forth in claim 4 wherein the boundarywall of the surge container has a peripherally extending fixing flangeat the side facing towards the inside wall of the container in theinstallation position.
 7. The method as set forth in claim 6 wherein thejoining surface of the fixing flange is profiled.
 8. The method as setforth in claim 7 wherein the joining surface of the fixing flange isprovided with melting projections and/or melting extension portionswhich melt to form said connection.
 9. The method as set forth in claim6 wherein the boundary wall of the surge container is flexible at leastin region-wise manner and at least portion-wise with respect to theperiphery of the surge container.
 10. The method as set forth in claim 9wherein the angle between the fixing flange and the boundary wall isvariable.
 11. The method as set forth in claim 4 wherein said surgecontainer includes one or more of connections, nipples and apertures forlines which are to pass into or out of said surge container.
 12. Themethod as set forth in claim 6 wherein said inside wall is provided withone or more inwardly projecting ribs which cooperate with one or moregrooves in said joining surface.
 13. The method as set forth in claim 6wherein said inside wall is provided with one or more grooves whichcooperate with one or more inwardly projecting ribs on said joiningsurface.
 14. The method as set forth in claim 1 wherein said connectionin melt-bonded relationship of said is at least one functionalinstallation fitment to said inside wall of the container requires noadditional thermal energy.